Prosecutors claim Robert Ferrante schemed to kill his wife, searching online for information about cyanide, a cheating spouse, and what a coroner might find in blood.

Ferrante's attorneys say he had nothing to do with Dr. Autumn Marie Klein's death in April 2013, after she collapsed at the couple's home in Oakland.

The homicide trial of Ferrante, a University of Pittsburgh researcher, is in its sixth day. Excerpts from the courtroom:

4:43 p.m.

Klein could have died from cyanide poisoning, but there could be other reasons she died, a medical toxicologist said Thursday.

Dr. Lewis S. Nelson, associate medical director for the New York City Poison Control Center, said Klein experienced several symptoms consistent with cyanide poisoning that are also symptomatic of other conditions.

"It's consistent, potentially, but there are enough inconsistencies" to point to something else, Nelson said.

Ferrante's lawyers called Nelson out of turn Thursday afternoon because he is not available next week. Nelson's testimony was recorded and will be played for jurors later.

3:03 p.m.

Ferrante told Sharon King that her cousin, Dr. Autumn Marie Klein, died of a "chemical storm" in her brain that caused her heart to fail.

"I had asked him questions about what was going on with her," said King, 44, of Bellingham, Wash., who choked back tears as she testified. "He said he has a lot of connections and was using his connections to find out the best way of what happened to her."

King said Ferrante never told her exactly how Klein died other than the chemical storm. "He said that was the best they could figure out," she said.

Prosecutors admitted into evidence several emails Klein sent to Ferrante on Feb. 9, 2013, in which she accuses him of not caring about how her fertility treatments were going.

"You have not been there for me," she wrote. "I don't know where to go from here. . I don't know what else to say Bob."

In another email Klein sent on Feb. 18, 2013, she requests that they "go out and talk" at some point in the near future.

"I don't know where things are going to go and you may not like what you hear, but I think it is about time we talked," she wrote.

Lyle Graber, a detective with the Allegheny County District Attorney's Office, testified that there were also emails forwarded from Klein's account to Ferrante's email address after she died in the hospital.

On April 22, 2013, an email was forwarded with the subject: "Google password assistance." The content of the email was not shown to the jury.

Graber also confirmed that Internet Protocol addresses that went along with several searches performed on a computer matched those of IP addresses Verizon assigned to Ferrante and Klein's home in Oakland.

12:12 p.m.

An analyst in the trace evidence section of the Allegheny County Medical Examiner's Office went through a variety of supplements, prescriptions and syringes Klein turned over to a friend in the months before her death.

UPMC neurologist Dr. Maria Baldwin testified this week that Klein gave her the fertility drugs she'd been taking in January 2013. Baldwin did not say why.

Nancy Love also talked about photographs of three bags and three small vials of creatine and four bottles of cyanide found in Ferrante's lab at Pitt.

Love said there were 187 grams remaining in a 500-gram bottle of potassium ferricyanide, in addition to a nearly-full 25 gram bottle of potassium cyanide, a leaking bottle of liquid cyanide and a 250-gram bottle of cyanide with 8.3 grams missing.

11 a.m.

The defense attorney for Ferrante continued Thursday to question the accuracy of cyanide blood test results from outside labs, pointing to a test that gave no results and a broken testing machine that didn't allow National Medical Services lab to provide a precise measurement of cyanide in Klein's blood during a second test.

Lab technicians from NMS, based in Montgomery County, testified about issues related to the testing of Klein's blood in the weeks after her death. The Allegheny County Medical Examiner's Office shipped samples of Klein's blood to that lab to get an exact measurement of how much cyanide was present. The Medical Examiner's Office found cyanide present in Klein's blood but didn't have the ability to get an exact measurement.

NMS analyst Linay Williams testified that during a test of a half-milliliter of Klein's blood on April 27, 2013, her "controls failed so I didn't get a result."

She entered the test failure into a computer database but apparently no one ever retested another portion of that sample. The Medical Examiner's Office then shipped another sample of Klein's blood, but analyst Rebecca Reber testified a machine that measures exact quantities of cyanide in blood was inoperable. Instead, she had to perform a test that only gives a range of projected cyanide levels.

The NMS analysts followed the testimony of two toxicologists from the Medical Examiner's Office - one who found cyanide in Klein's whole blood and one who found cyanide in Klein's plasma.